Backlight illumination modules of the Liquid crystal display (LCD) is one of specific applications of illumination modules, and also one of basic components of LCD. Currently, many types of backlight illumination modules are used in practice. For example, in a conventional side-lit backlight illumination module, light emitting diodes (LEDs) are disposed on both sides of the backlight illumination module, and a light guide is provided in the display area of the LCD display, and thus the light emitted by the LEDs at two ends of the backlight illumination module can be uniformly irradiated out of the backlight illumination module via the light guide. In a direct-lit backlight illumination module, a plurality of LEDs is provided in the display area of the LCD display directly, so the light guide is not required. However, the half-power angle of the radiation of each LED is about 120°. Therefore, in a direct-lit backlight illumination module, a distance must be reserved above the LEDs so as to allow the light emitted by two neighboring LEDs to be partially overlapping. The two types of backlight illumination modules mentioned above have their advantages and disadvantages respectively. The side-lit backlight illumination module employing the light guide is usually heavier than the direct-lit backlight illumination module; however, the LEDs in the side-lit backlight illumination module are arranged less densely than those in the direct-lit backlight illumination module. Since the direct-lit backlight illumination module requires a long light-mixing distance, it is relatively thick; on the other hand, the direct-lit backlight illumination module also requires an additional circuit board. Therefore, the cost of the overall structure of the direct-lit backlight illumination module is higher. The illumination module not only can be used in LCD, but also can be used in planar light source for the general illumination because of the similar principle. Therefore only the examples of illumination module used in a LED display are provided herein.
Illumination modules with increased LED pitch are provided in US Patent Publication Nos. 2005/0007758A1, 2005/0140848A1 and U.S. Pat. No. 6,966,644. Firstly, US Patent Publication No. 2005/0007758A1 provides a strip-shaped light guide with a plurality of openings, and an LED is disposed at two ends of the light guiding strip respectively. When the LEDs emit light, a plurality of openings of the light guide will radiate light to simulate a plurality of LEDs. Further, US Patent Publication No. 2005/0140548A1 provides an illumination module with a plurality of strip-shaped light guides, which is advantageous in that the brightness of the illumination module can be adjusted by individually driving the selected light guide. Moreover, U.S. Pat. No. 6,966,664 provides a light guiding strip, in which the light emitted by LEDs at two ends of the light guiding strip is concentratedly irradiated out from a arced surface of the light guiding strip, so as to form a linear and uniform light source.
In view of the above, light guiding strips in the art and the backlight illumination module and display using the light guiding strip have the shortcomings of being thick and heavy or having a high cost, so it is necessary to provide a light, thin, and low-cost light guiding strip and an illumination module and display using the light guiding strip.